Apparatus for producing sound



May 25, 1965 G. M. GIANNINI ETAL APPARATUS FOR PRODUCING SOUND 2 Sheets-Sheet 1 Filed May 1, 1962 INVENTORS 6058/62 144. GW/V/Vl/V/ Amen/v0 0. 000077 BY E. f Z

07700/VEV y 25, 1965 G. M. GIANNINI ETAL 3,185,778

APPARATUS FOR PRODUCING SOUND Filed May 1, 1962 2 Sheets-Sheet 2 FIG. 2.

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INVENTOR. male/62 Mam/MM Swaz- BY;

United States Patent:

3,185,778 APPARATUS FOR PRODUCING SOUND Gabriel M. Giannini and Adriano C. Ducati, Newport Beach, Calif., assignors, by mesne assignments, to Giannini Scientific Corporation, Amityville, Long Island, N.Y., a corporation of Delaware Filed May 1, 1962, Ser. No. 191,549 6 Claims. (Cl. 179-113) This invention relates to an apparatus for producing sounds, including extremely loud sounds such as warning noises, as well as speech and music. This application is a continuation-in-part of our co-pending application Serial No. 775,979, filed November 24, 1958, for Apparatus and Method for Producing Sound, now abandoned.

There are a number of situations in which it is highly desirable to produce very loud noises, for example to give air raid warnings. There are also situations in which it is desirable to produce various acoustical effects, includ- 'ing speech and music, which are audible at a large dismusic, in a highly efficient manner.

A further object is to provide an apparatus incorporating an electrical plasma jet or flame to produce different types of sounds in various volume ranges up to the very highest.

A further object of the invention is to provide an apparatus whereby an electrical plasma jet may be employed to produce extremely loud sounds, and may be associated with electrical or gas-modulation means to produce speech and music.

These and other objects and'advantages of the present invention will be more fully set forth in the following specification and claims, considered in connection with the attached drawings to which they relate.

In the drawings:

FIGURE 1 is a schematic longitudinal central sectional view of a first form of sound-producing apparatus constructed in accordance with the present invention;

FIGURE 2 is a schematic side-elevational view illustrating a second embodiment of the invention; and

FIGURE 3 is a schematic representation of a third embodiment of the invention, in which means are provided to modulate the flow of gas to the plasma torch.

Referring first to the embodiment of FIGURE 1, an electrical plasma-jet torch is indicated schematically at as comprising a generally cup-shaped nozzle electrode 11 having a generally disc-shaped back electrode 12 mounted coaxially therein. Nozzle electrode 11 has a central nozzle opening 13, the wall of which is protected by a tube 14 formed of a suitable refractory metal such as tungsten. The central arcing portion of the back electrode is similarly protected by means of an insert 15 formed of tungsten or the like.

The back electrode 12 is mounted in electrical contact with a base 17, such elements being maintained in assembled relationship by means of a retaining ring 18. Insulation means 19 are provided to insulate the electrodes from each other. The base, and the nozzle and back electrodes 11 and 12, are all formed of highly-conductive metal such as copper.

' within the audio range. 45

* 3,185,778 Patented May 25, 1965 ice Means are provided to cool the electrodes, and comprise suitable chambers 21 and 22 formed in the nozzle and back electrodes, respectively, adjacent the arcing portions thereof. Conduit and passage means 23 are provided to pass a coolant, such as water, through the chambers.

A high-current electrical power source, indicated schematically at 24, is connected through cables 26 and 27 to the nozzle and back electrodes, respectively. When the power source is applied, and after arc initiation in a suitable manner such as by inserting a thin stick of graphite between the electrodes, a high-current electric arc is maintained between the refractory inserts 14 and 15. Such are passes through a gas-pressure chamber which is annular in shape and coaxial with nozzle opening 13, being indicated at 28. Power source 24, and source 36 to be described subsequently, supply at least on the order of fifty amperes of current to the water-cooled electrodes. Preferably, the current is on the order of hundreds or thousands of amperes.

A suitable gas source, preferably containing an oxidation-preventing gas such as argon, under substantial pressure, is indicated schematically at 29 and is connected through a conduit 31 and inlet opening 32 to the gaspressure chamber 28. Conduit 31 is tangential to chamber 28, so that gas introduced at high velocity through inlet opening 32 flows vortically in the chamber and then passes out the nozzle opening 13.

When the gas is introduced at sufiicient pressure, it

' serves to constrict the electric arc to the vortex in the whirling gas, that is to say to reduce the cross-sectional area of the arc in comparison to the area it would normally occupy in the ambient atmosphere. The current density and temperature of the are are thus greatly increased, and effect heating of the gas to a high temperature. An electrical plasma jet or flame, indicated at 33 and consisting of hot neutral gas, ions and electrons, is thus caused to flow at high velocity out the nozzle opening.

The plasma jet 33 is caused to discharge axially into an elongated horn 34 which effects direction and magnification of the noise created by the jet. More specifically, the power source 24 is caused to be a source of alternating or pulsating current having a predetermined frequency The horn 34 has such a shape, size and construction that it will resonate to such predetermined frequency and will accordingly greatly augment the sound produced by the torch. The volume of the sound may be increased to enormous amounts by increasing the size of the torch, the amount of electrical power fed thereto, etc. In this manner a sound may be produced which may be heard for miles.

Referring next to the embodiment of FIGURE 2, the torch 10 is the same as was described in connection with the previous embodiment. A DC. power source 36 is connected to the cables 26 and 27, there being a suitable modulator 37 interposed in cable 26 as schematically indicated.

The DC. source 36 comprises a very smooth, noise-free source of power to result in a very steady nad stable noisefree electric arc in the torch 10. For example, the DC. power source may comprise a well-built generator and filter combination adapted to avoid self-oscillation and maintain the electric are absolutely steady. Power source 36 may also comprise a special battery.

The modulator 37 is of a suitable type adapted to superimpose on the voltage from source 36 a modulating voltage which may represent speech or music. In this manner, the current supplied to torch 10 is a representation of speech or music and causes the electric arc in the torch to vary accordingly. This, in turn, varies the sound generated by the torch, which sound is transmitted through the horn 34a to the listener as speech or music. The gas =3 is introduced in a steady flow from source 29 (FIGURE 1) through inlet conduit 31.

Referring next to the embodiment of FIGURE 3, the gas flow through condnit 31 is modulated by a gas modulator indicated at 38. The electric power source in the embodiment of FIGURE 3 may be the steady D.C. source 36 employed in the embodiment of FIGURE 2.

The gas modulator 38 may comprise, as schematically shown in FIGURE 3, a fixedly supported inner tube 41 on which is slidably mounted an outer tube or sleeve 42 formed of magnetizable material. Such tubes have openings 43 and 44, respectively, adapted to register in varying degrees depending upon the longitudinal position of the sleeve 42 on the inner tube 41. Since the inner tube 41 has a closed end 46, the only way that gas introduced into the inner tube may enter an outlet chamber 47 is through the openings 43 and 44. The inlet end of tube 41 is adapted to receive gas from a conduit 48 connected to a suitable steady gas-pressure source, not shown. The outlet chamber 47 is connected to the conduit means 31, previously described. Means, not shown, are provided to permit the sleeve 42 to slide relative to the wall of chamber 47 in a frictionless manner.

Electromagnetic actuating means, schematically represented as a coil 49, are adapted to effect longitudinal movement of sleeve 42 on tube 41 in response to electrical current fed thereto from a suitable source 51 through leads 52 and 53. Power source 51 is adapted to transmit a current which varies (in the audio range) in accordance with various sounds including speech and music. It follows that the degree of registry between openings 43 and 44 will vary in accordance with the audio current delivered to coil 49 from source 51, causing a corresponding variation in the flow of gas to outlet chamber 47 and thence through conduit 31 to the gas-pressure chamber 28 in the torch. This, in turn, produces a corresponding effect upon the plasma jet 33 and upon the sound generated by the torch.

Throughout the specification and claims, the term resonate, etc., employed with reference to the horn, denotes that the horn is shaped for effective and etficient interaction with the plasma torch in such manner as to produce the desired sound.

It is pointed out that the above-described modification or modulation of the high-current arc momentarily changes the size thereof, the are expanding, contracting and changing in temperature, in accordance with the modulation. The temperature changes, expansions and contractions of the arc affect the size, temperature and other characteristics of the plasma jet 33. Thus, both the arc and plasma jet are modulated, and produce sound which may comprise speech, music or a warning signal.

Various embodiments of the present invention, in addition to what has been illustrated and described in detail, may be employed without departing from the scope of the accompanying claims.

We claim: 7

1. Apparatus for producing sound, which comprises a nozzle element having a nozzle passage therethrough, electrode means including a back electrode having an arcing portion disposed in the vicinity of said nozzle passage, means to effect cooling of said electrode means, currentsupply means connected electrically to said electrode means to maintain a high-current electric arc from said arcing portion through at least a portion of said nozzle passage, said current-supply means being adapted to supply'at least on the order of fifty amperes current to said electrode means, a source of gas under substantial pressure, conduit means connecting said source to said nozzle passage to effect forced flow of gas therethrough whereby said gas is heated substantially by said are and is discharged from said nozzle passage in the form of plasma, and means to alter the characteristics of said are and thus of said plasma at frequencies within the audio range to thereby effect generation of sound.

2. The invention as claimed in claim 1, in which said last-named means is a means to efiect said alteration of said arc and plasma in a manner representing speech or music.

3. The invention as claimed in claim 1, in which said nozzle is electrically conductive and forms part of said electrode means, and in which said current-supply means is adapted to supply current on the order of at least hundreds of amperes.

4. The invention as claimed in claim 1, in which mechanical horn means are mounted in communication with said nozzle passage to effect magnification of the sound emanating from said arc and plasma.

5. The invention as claimed in claim 1, in which said conduit means is so related to said nozzle passage that said gas flows vortically about the axis of said nozzle passage.

6. The invention as claimed in claim 1, in which the gas contained in said source is an oxidation-preventing gas.

No references cited.

ROBERT H. ROSE, Primary Examiner. 

1. APPARATUS FOR PRODUCING SOUND, WHICH COMPRISES A NOZZLE ELEMENT HAVING A NOZZLE PASSAGE THERETHROUGH, ELECTRODE MEANS INCLUDING A BACK ELECTRODE HAVING AN ARCING PORTION DISPOSED IN THE VICINITY OF SAID NOZZLE PASSAGE, MEANS TO EFFECT COOLING OF SAID ELECTRODE MEANS, CURRENTSUPPLY MEANS CONNECTED ELECTRICALLY TO SAID ELECTRODE MEANS TO MAINTAIN A HIGH-CURRENT ELECTRIC ARC FROM SAID ARCING PORTION THROUGH AT LEAST A PORTION OF SAID NOZZLE PASSAGE, SAID CURRENT-SUPPLY MEANS BEING ADAPTED TO SUPPLY AT LEAST ON THE OTHER OF FIFTY AMPERES CURRENT TO SAID ELECTRODE MEANS, A SOURCE OF GAS UNDER SUBSTANTIAL PRESURE, CONDUIT MEANS CONNECTING SAID SOURCE TO SAID NOZZLE PASSAGE TO EFFECT FORCED FLOW OF GAS THERETHROUGH WHEREBY SAID GAS IS HEATED SUBSTANTIALLY BY SAID ARC AND IS DISCHARGED FROM SAID NOZZLE PASSAGE IN THE FORM OF PLASMA, AND MEANS TO ALTER THE CHARACTERISTICS OF SAID ARC AND THUS OF SAID PLASMA AT FREQUENCIES WITHIN THE AUDIO RANGE TO THEREBY EFFECT GENERATION OF SOUND. 